Even when compared to the size of their host galaxies, black holes today are far larger than they were nine billion years ago, according to observations. Astrophysicists have discovered a theory for dark energy, the enigmatic factor responsible for the universe’s ever-increasing rate of disintegration, in an effort to explain the size of this anomaly. Actually, the source might be black holes.
When scientists utilized the apparent brightness of supernova explosions to gauge the rate of the universe’s expansion, they anticipated that it would slow down, but they just needed to know by how much. They were shocked to discover that it was speeding up instead.
Only a small minority of physicists are still skeptical, but the evidence has been amply supported, and there is broad consensus that dark energy is to blame for the acceleration that has been observed.
However, it is still unclear what dark energy is and where it comes from. There have been numerous attempts to provide an answer to this; however, none have been particularly successful. The Nobel Prize is guaranteed for anyone who accomplishes so. With two new articles, an international collaboration from nine countries hopes to change that.
Their articles were the result of a discovery that wasn’t particularly on the researchers’ radar when they first started, similar to the discovery of dark energy. In a statement, Dr. Dave Clements of Imperial College London said, “This is a truly surprising result.” We began by examining the evolution of black holes, and we believe we may have discovered the solution to one of cosmology’s most pressing issues.
Why do we observe gravity drawing objects together if there is a force pushing the cosmos apart? sums up a major barrier to comprehending dark energy. The one thing we do know about dark energy is that, at least substantially, it seems to only apply at extremely large scales, where other forces predominate closer in.
Therefore, supermassive black holes offer an intriguing test case because they draw matter from such vast distances that we might be able to observe the transition between the dominance of gravity and dark energy in a way that is hidden by smaller objects.
From what we can observe, black hole propagation is too sluggish and irregular to be measured. However, we can estimate average growth rates by comparing the mass of a sample of far-off black holes to that of close black holes in neighboring galaxies.
In one study, the team notes that, in relation to the size of their host galaxies, the nearby samples have an average mass that is seven to twenty times that of those observed nine billion years ago. Except for evaporation through Hawking Radiation, that growth rate is inconsistent with what we know about star merger rates and consumption.
However, black holes would expand more quickly if they had vacuum energy connected to the universe’s expansion. Indeed, according to the authors’ calculations, the majority of what we believe to exist would be explained if supermassive black holes at the centers of galaxies were to produce dark energy. Halos and possibly stellar black holes in galaxy disks could make up the remainder.
Dr. Duncan Farrah of the University of Hawaii remarked, “We’re essentially saying two things at once: that there’s evidence the traditional black hole solutions don’t work for you on a long, long period, and we have the first proposed astrophysical source for dark energy.” That doesn’t mean that other people haven’t suggested sources for dark energy; rather, it only means that this is the first observational work in which we don’t contribute anything new to the cosmos as a source for dark energy; in Einstein’s theory of gravity, black holes are the dark energy.
The authors admit the likelihood that such a significant claim may be scrutinized more than the average paper: “Selection and measurement biases are both underestimated.” They also suggest a few potential tests for the future that might confirm or refute their notion. However, they rule out a number of potential explanations for the sudden growth as being unlikely, leaving the strongest contender to be black holes acting as dark energy manufacturers.
The long-standing adage that “More massive black holes prefer to reside in more massive galaxies” holds true in our local universe is crucial to the discovery. In order to rule out the possibility that the black holes in this study had grown through more mergers than anticipated or that the team was somehow studying undersized galaxies from billions of years ago, the black hole masses in this study were compared with the mass of the visible stars in the galaxy.